This invention relates to a door for a coke oven chamber and more particularly, to such a door forming a heat-resistant plug consisting of a door-body plate external to the oven chamber and steel plates extending in the oven chamber and arranged with one end displaceable for heat-insulating purposes.
Doors of this type are particularly useful for coke ovens having walls provided with heating flues which, in contrast to the design of reverberatory furnaces with a quenched furnace charge and having first heating flues set back in the furnace walls, comprise heating flues which are set forwardly in the heating walls and mechanical leveling of the charge in the furnace takes place. The chamber doors for coke ovens provide flameproof plugs which serve to reduce the release of heat to the outside from the door plates, usually made of cast iron, to such an extent that the door body structure will not bend. The chamber doors also reduce preheating stresses due to the forward, first heating flues on the oven parts, namely on the oven heads and particularly on the buckstays located in the area of the first heating flue by maintaining the glowing coke sufficiently faraway from the area.
In known door designs for coke ovens of this type, the plug consists of refractory material which, for example, may be in the form of brickwork resting on a lower brickholder and secured by lateral brickholders to the door or in the form of molded brick which is, for example, bolted to the door-body plate. The first heating flue in the wall of the coking chamber is usually located behind outwardly-directed brickwork preferably made of slightly acidic brick and supported outside the furnace by a layer of heat-insulating material upon buckstays. The door frame is carried by brickwork that is usually interchangeable. When the door is closed, the inside of the fireproof plug material projects into the oven chamber to the first heating flue. This protects the door seal from the heat of the first heating flue and the heat of the coke cake. To accelerate carbonization of the coal charge in the head parts of the coke oven, and thus obtaining uniform coking of the coal charge, it has been proposed as disclosed by West German patent publication No. OS 30 00 161, to provide the furnace side of the plug with a coating having a degree of heat conductivity which is greater than the material of the plug. The overall dimension of the door plug is reduced by the thickness of the coating so that the coating does not change the overall dimension of the door plug.
Thermal expansion of the coating, arising during the coking process, may be compensated for by the use of metal plates arranged as a covering. In this way, the supporting surface of the door plug becomes the heating surface and brings about better carbonization of the top part of the coal charge in the oven chamber. An air or gas chamber may be formed between the door plug and the steel plates. The low heat conductivity of the enclosed air or gas in this chamber may be used, outstandingly, for heat insulation. The distance between the door body and the steel plates may be varied according to the permissible surface temperature of the door body. According to a known design, the steel plates have T-shaped stiffeners. The plates are arranged with their ends overlapping each other in the downward direction. The lower ends of the plates can expand freely. When the height of a coke oven chamber is 4 meters, the steel plates should be no longer than 1 meter. As the height of the coke oven chamber increases, the length of the steel plates is decreased to one-tenth of the oven chamber height. Thus, when the height of an oven chamber is 7 meters, the length of the steel plates is 0.7 meter at most. As a result of reoccurring problems, the operational reliability of this door design is far lower than that of conventional door plugs. Damage to the door plug is concentrated in the lower part of the plates.